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1.
The tectonic evolution of a large, complex, mobile region in Central and mountainous Asia is summarized and documented from early Paleozoic to Middle Tertiary. Four basic stages are recognized: the epi-Proterozoic platform, the geosyncline, the young platform, and the activated platform. Generally, the timing coincides with late Precambrian, middle-late Paleozoic, middle-late Mesozoic, and Cenozoic, respectively. Each of these stages started and finished at different times in different parts of the composite mobile belt. The sedimentary, volcanic, and orogenic record is summarized and interrelated in the northern Tien-Shan, Central Tien-Shan, southern Tien-Shan, Kun-Lun and northern Pamir, southern Pamir and Karakorum, and Himalayan provinces. — L.T. Grose.  相似文献   

2.
帕米尔东北缘地区构造变形特征与盆山结构   总被引:7,自引:0,他引:7  
帕米尔东北缘乌泊尔地区是正确认识帕米尔北缘盆山结构和构造变形特征非常关键的地区,本文利用连续电磁剖面(CEMP)资料和地震资料,并结合野外地质调查资料和钻井资料,对帕米尔东北缘乌泊尔地区的盆山结构和构造变形特征进行了研究。认为帕米尔东北缘及其以北地区的盆山结构表现为帕米尔造山带向北冲断和南天山向南冲断所形成的对冲结构;帕米尔山前为基底卷入式构造,古生界—中生界沿高角度的逆冲断层推覆到新近系和第四系之上,形成山前的古生界—中生界逆冲推覆带;北侧由受乌泊尔断裂控制的深部隐伏冲断体系和浅部的第四纪背驮盆地所构成。研究区的新生代构造变形时间开始于上新世晚期,并持续变形至今,形成了下更新统西域组(Q_1x)与下伏上新统、Q_2与Q_1和Q_(3-4)与Q_2之间的不整合。研究区最小构造缩短量为48.6 km,缩短率为48.1%。  相似文献   

3.
KINEMATICS OF QUATERNARY EXTENSION IN THE PAMIR1 BurtmanVS ,MolnarP .GeologicalandgeophysicalevidencefordeepsubductionofcontinentalcrustbeneaththePamir[J].SpecPapGeolSocAm ,1993,2 81:76 . 2 StreckerMR ,FrischW ,HamburgerMW ,etal.QuaternarydeformationintheEasternPamirs ,TadzhikistanandKyrgyzs tan[J].Tectonics,1995 ,14(5 ) :10 6 1~ 10 79.…  相似文献   

4.
乌泊尔断裂带位于帕米尔构造结东北缘,作为揭示青藏高原形成与演化历史的关键地区之一,为碰撞造山作用提供了详细信息,因此厘清乌泊尔断裂带关键构造的形成演化具有重要意义。为研究该断裂带的几何学与运动学特征,本文利用钻测井资料、二维地震反射资料、DEM 高程资料以及喀什地区1∶100 000地质图,以断层相关褶皱理论为指导,对乌泊尔断裂带进行精细构造解析。研究认为,乌泊尔断裂沿走向至少可分为东、西两段,西段构造变形强烈,而东段较弱,构造样式沿断裂走向上有较大差异;垂直于构造走向上可划分出两个等倾角区;乌泊尔地区的变形最早于中新世早期开始,自上新世以来构造变形强烈,乌泊尔断裂在该区域的活动起始于第四纪,具有幕式活动的特点;通过断层相关褶皱分析得到,自中新世至上新世,断裂东段的构造缩短量至少为9.47 km,第四纪以来的构造缩短量至少为11.65 km。第四系生长地层的内部结构受控于基底叠瓦构造和乌泊尔断裂,明确深浅构造的关系能较好得限定研究区关键构造的形成演化过程,可作为复杂构造解析的有效方法。  相似文献   

5.
Surface processes involve complex feedback effects between tectonic and climatic influences in the high mountains of Pamir. The ongoing India–Asia collision provokes the development of east–west-trending mountain ranges that impose structural control on flow directions of the Pamir rivers. The evolving relief is further controlled by strong moisture gradients. The decreasing precipitations from the southern and western margins of the Pamir Plateau to its center, in their turn, control the emplacement of glaciers. Chronologies of glacial records from the Pamir Plateau attest for strong climatic variability during the Quaternary. Corresponding remnants of glacial advances suggest glacial morphodynamic restricted to >4,000 m a.s.l. since marine isotope stage 4. The Panj, the trunk river of Pamir, deflects from the predominant westward drainage, connecting its main tributaries at the western margin of the drainage basin. The geometry of the river network and the pattern of incision characterize the Panj as a composite river. River reaches of indicated low incision coincide with west-trending valleys, parallel to domes and their bounding faults. Valley shape ratios reflect increased incision in north-trending sections, but do not match with changes in the catchment geometry or erodibility of rock types. Modelled riverbed profiles distinguish three Panj reaches. The upstream increase in convexity suggests successive river captures in response to local base-level changes. The northward-deflected river reaches link the local base levels, which coincide with the southern boundaries of the Shakhdara and Yazgulom Dome and Darvaz Range. We argue that tectonics plays a large role controlling the drainage system of the Panj and hence surface processes in the Pamir mountains.  相似文献   

6.
杨科佑 《第四纪研究》1996,16(3):272-276
第四纪最突出的事件是青藏高原和南海海盆的形成和演化。众多中外学者几乎一致认为,青藏高原的形成是由于印度克拉通向北的推动,南海等西太平洋边缘海是在太平洋板块和菲律宾海板块向西俯冲的过程中形成的。笔者另辟蹊径,提出,由于新生代(尤其是第四纪)以来两个相互交切的东亚断裂和南亚断裂的深部物理运动,使得南海等西太平洋边缘海地区的陆壳物质被逐渐吸入地幔,经转化为“幔源壳质”以后,再不断输送、补充给青藏地区。其结果必然是,南海等西太平洋边缘海地区的陆壳迅速转化为过渡型壳甚至洋壳,青藏地区则由洋壳转化为陆壳,并迅速隆起、增厚。  相似文献   

7.
东北平原第四纪环境演化与荒漠化问题   总被引:43,自引:4,他引:39  
林年丰  汤洁 《第四纪研究》1999,19(5):448-455
东北平原是中国最大的平原,也是全国著名的粮仓。半个世纪以来,荒漠化发展的速度很快,严重影响社会经济的可持续发展。构造一气候旋回,冰期一间冰期气候的波动对第四纪环境的演化起了关键作用,干冷气候可导致沙漠化的发展,湿润气候促使土壤和植被发育,对沙漠化起到了抑制作用。自晚更新世以来,在干、湿气候交替出现的过程中,土壤的苏打化过程和脱苏打化过程也在交替进行。东北平原的沙质荒漠和盐碱荒漠主要是因为人们对土被、植被的破坏所造成的。东北平原是对世纪重要的经济开发区,研究治理该区的荒漠化有重要的战略意义。  相似文献   

8.
The position of the Pamirs and the Hissar–Alai mountainous system in the structure of Central Asia and features of their junction are considered. It is shown that their outer contours and tectonic infrastructure are significantly distinct in the planar pattern: latitudinally linear and arched for the Hissar–Alai and the Pamirs, respectively. These structures logically match those of the Central Asian and Alpine–Himalayan belts, respectively. The Pamir orogen is a relatively autonomous structural element of the crust, which is located discordantly relative to the country lithospheric blocks. Most of the Pamirs (at least, the Northern and Central) probably form a giant allochthon on the ancient basement of the Tarim and Afghan–Tajik blocks. The junction zone of these two “hard” crustal segments is reflected in the transverse Transpamir threshold, which is expressed in the relief, deep structure, and seismicity. The specific geological structure of the junction zone of the Pamirs and Hissar–Alai (systems of the Tarim, Alai, and Afghan–Tajik troughs) is shown. It suggested that this zone is a damper, which significantly neutralizes the dynamic influence of the Pamir and the southernmost elements of the Pamir–Punjab syntax on Hissar–Alai structures.  相似文献   

9.
松辽盆地是中国东北盆地群的代表性盆地之一。松辽盆地及其邻区的布格重力异常分布特征以北东—北北东向为 主,其次为东西向,重力场分区分块特征明显,显示了明显的拼贴构造背景,依据布格重力异常特征对研究区构造单元进 行分区,共分成松辽盆地异常区、大兴安岭重力梯级带等 5 个特征区。利用小波多尺度分解方法对松辽盆地重力场进行分 离,选择最佳的分离阶数(4 阶),随后利用对数功率谱确定每阶异常的视深度,提取区域异常,分层研究地壳顶部(D1G)、基 底(D2G,D3G)及深部密度界面(A4G)的起伏特征,共圈定基底凹陷 14 个,并绘制了研究区的 Moho 面埋深图。地球物理特征 揭示了松辽盆地的深部构造,为研究盆地油气勘探及构造演化提供了重要依据。  相似文献   

10.
This article discusses the main results of neotectonic investigations in the Polish Carpathians. Longitudinal elevations and isolated blocks have been uplifted at different rates, ranging from 0.05 to 0.3 mm/yr. Intramontane basins and longitudinal depressions reveal subsidence attaining 0.12 mm/yr. Present-day velocities of vertical movements attain 3 mm annually while the contemporary thrusting of the Carpathians onto their foreland is from 2 to 6 mm/yr.Four Quaternary episodes of increased tectonic activity have been distinguished: at the Pliocene—Pleistocene boundary, in the Early Pleistocene, before the Matuyama—Brunnes boundary and during the Holsteinian Interglacial. The latter is thought to be the most prominent.  相似文献   

11.
THE NORTHWARD PROPAGATION OF THE ARC TECTONICS OF THE NORTHEAST PAMIR AND NORTHWEST TARIM BASINThisworkispartoftheresearchproject“themechanismofJiashistrongearthquakeswarmandprediction ofearthquakeriskinthenortheastPamir  相似文献   

12.
《Quaternary Science Reviews》2007,26(22-24):2758-2782
The paper discusses the Quaternary evolution of the Danube and Tisza rivers and their main tributaries in the context of evolution of the entire Pannonian Basin, which is Europe's largest intramontane basin, within the Alp–Carpathian orogen. The palaeo-drainage reconstruction of the Pannonian Basin for the pre-Quaternary period is outlined in connection with the gradual regression of Lake Pannon since the Late Miocene. Deltas of rivers that entered the basin from the northwest and northeast were gradually transformed into extended alluvial plains; thus, the earliest possible ancestor of the Danube coming southeastwards from the Alps could be as old as Late Miocene. By the Pliocene the whole Lake Pannon was infilled. The former extensional basin formation was replaced by a compresional stress field, which resulted in an uplift of the marginal flanks and late-stage subsidence anomalies. The increasing relief led to the formation of the Quaternary drainage pattern. The actively subsiding young basins were filled by fluvial sediments, transported by the Danube and Tisza river systems from the uplifting mountains. Between the subsiding regions of the Little and Great Plains, the Danube has formed an antecedent valley with terrace staircases between the uplifting sections of the Transdanubian Range and the North Midmountains. The formation of the terraces is attributed to periodic climate changes during the Pleistocene combined with differences in the uplift rate. The paper gives a complex overview of the classical chronology of the six terraces based on various data sources: mostly dating of loess/paleosol sequences, travertines, aeolian sand, and tephra strata overlying the fluvial sediments, complemented by scattered vertebrate faunal data and archaeological evidence directly from the terrace sediments.The Quaternary drainage pattern evolution of the Great Plain, with a strong tectonic control, is discussed in detail. Rivers originating from the uplifting marginal areas were drawn towards the subsiding depressions which served as local base level. Changes in subsidence rates in space and time throughout the Quaternary resulted in the evolution of a complex drainage pattern. A special emphasis is placed on the Late Pleistocene–Holocene development of the Middle–Tisza region and the Körös basin, where the Berettyó–Körös Rivers form an eastern tributary system of the Tisza River. A comparative evaluation of these two areas is especially relevant, as they provide insights into large-scale Late Pleistocene avulsion of the Tisza River. OSL dating, complemented with inferred transport directions determined from heavy mineral analysis of fluvial sediments in the Körös basin, has revealed an ancient large meandering river system that can be identified with the palaeo-Tisza, which was flowing along a tectonically controlled depression during the Late Pleniglacial. Successions in the Middle Tisza region have allowed differentiation between the older channels of the palaeo-Bodrog River and the Sajó–Hernád alluvial fan and the younger meander belts of the new course of the Tisza. In the Tisza system, changes in river style (braided to various scales of meandering) show correspondence to millennial-scale climate changes of the last 25 ka, while in the Körös basin the effects of tectonics are overprinted onto the regional climatic signals.  相似文献   

13.
第四纪洞庭盆地澧县凹陷构造活动特征及动力学机制探讨   总被引:11,自引:0,他引:11  
第四纪澧县凹陷为洞庭盆地西北部的一个次级凹陷.通过地表观察和钻孔资料,对澧县凹陷及周缘第四纪沉积物和地貌及其反映的构造活动特征进行了研究,进而探讨构造活动的动力机制.澧县凹陷呈由南、北西、北东边界正断裂所限的三角形.早更新世.中更新世中期,边界正断裂强烈活动,凹陷区大幅沉降,充填了一套以砂砾层为主的沉积,其厚度自凹陷边缘向中央增加;正断裂下盘局部存在较大幅度沉降.与此同时,澧县凹陷南面、西面的外围地区产生构造抬升,形成由冲积层组成的多级基座阶地.中更新世晚期开始凹陷区及周缘地带整体抬升,凹陷区北部及凹陷南缘产生自西向东的掀斜,凹陷区北部形成小型褶皱构造.上述构造活动特征指示澧县凹陷在早更新世.中更新世中期具断陷盆地性质,中更新世晚期以来具拗陷盆地性质.提出早更新世-中更新世中期构造活动与地幔上隆有关:深部地幔上涌对地壳加热,使凹陷区中地壳韧塑性物质膨胀而向周边侧向迁移,尔后冷却收缩致上层地壳"塌陷"而产生整体性下拗沉降,并于下沉块体侧翼发育正断裂.此外,重力均衡机制可能也起到一定作用.中更新世晚期以来的构造活动可能与深部物质蠕移运动的弹性回返以及板块尺度的物质运动和挤压作用有关.  相似文献   

14.
第四纪华容隆起构造活动、成因及动力机制   总被引:9,自引:0,他引:9  
第四纪华容隆起位于江汉—洞庭盆地中部。通过地表观察和第四系钻孔对华容隆起及周缘地貌、第四纪断裂和沉积进行调查,恢复华容隆起构造升降特征与过程,进而探讨华容隆起的成因及其构造活动的动力机制。研究表明:早更新世-中更新世中期华容隆起与周缘凹陷一道沉降,同时前者受周边正断裂控制相对后者有抬升,中更新世晚期一道抬升,晚更新世—全新世构造稳定或弱沉降。第四纪期间华容隆起总体表现为明显的构造沉降。以上表明第四纪华容隆起主要由前第四纪盆—山地貌分异造成,其次与第四纪期间相对周缘凹陷抬升有关。上述地质特征以及区域第四纪地质资料,表明早更新世-中更新世中期江汉—洞庭盆地为断陷盆地,中更新世晚期—全新世转变为坳陷盆地。就华容隆起第四纪构造活动的动力机制进行了探讨并提出:1)早更新世-中更新世中期江汉—洞庭盆地断陷沉降与地幔上隆背景下的深部物质迁出有关。2)中更新世晚期以来的构造活动可能与深部物质蠕移运动的回返以及板块尺度的物质运动和挤压作用有关。3)江汉—洞庭盆地的整体性沉降导致盆地中部的华容隆起以沉降为主;华容隆起特殊的地壳物质结构可能导致深部物质更难向外迁移,使其相对周缘凹陷有抬升。  相似文献   

15.
本文阐述了遥感影象线性构造在研究区域构造和深层构造中的地质意义,探讨线性构造与区域构造轮廓间的关系。地壳的构造变形常以丰富的构造地貌景观和线性构造信息显示在遥感图象上。这种深部构造信息也有可能通过地壳的动力变形和深部地球化学反应传递到地表。文中详述了这些线性构造和深层构造及岩浆涌动构造间的内在联系。  相似文献   

16.
During 1973–1977, as part of the International Geodynamic Project, some seismic investigations of the Earth's crust have been carried out by geotraverses of the Tien Shan—Pamirs—Karakorum—Himalayas. The seismic data obtained together with other geophysical information, allow the construction and interpretation of the lithospheric section through the Pamirs-Himalayas structure. This section includes thick crust with complex layering, supra-asthenospheric and asthenospheric layers of the upper mantle. The thickness of the Earth's crust increases from 50–55 km in the north, in the Ferghana depression (Tien Shan), to 70–75 km in the south, near the Karakul Lake (Northern Pamir). It varies within 60–65 km for the Central and Southern Pamir, Karakorum and the Inner Himalayas. Its thickness is least (35–37 km) in the south, under the outer margin of the Himalayan foredeep. Extreme gravity minima and depressions on the geoid surface correspond to the regions with maximum thickness of the Earth's crust. The centers of the disturbing masses on the geoid surface are located in the vicinity of the asthenosphere's upper layer; this determines the effect of the whole lithospheric layer, including its asthenospheric layer, at intense changes of gravity anomalies. The asthenospheric upper layer is recorded at a depth of about 120 km, its base at a depth of 200 km, in the northern and southern regions, and 300 km in its central part (Southern Pamir, Karakorum). In the middle asthenospheric layer, wave velocities decrease to 7.5 km/sec, under the base they increase to 8.4 km/sec and reach 9.4 km/sec at a depth of about 400 km. In the supra-asthenospheric layer of the upper mantle, longitudinal and shear wave-velocities slightly increase (by less than 0.1 km/sec) towards its base.  相似文献   

17.
The tectonic evolution of the Mt Amiata volcano-geothermal area is under discussion. Some authors state that this region, as well as the hinterland of the Northern Apennines, were affected by compression from the Cretaceous to the Quaternary. In contrast, most authors believe that extension drove the tectonic evolution of the Northern Apennines from the Early Miocene to the Quaternary. Field data, seismic analyses and borehole logs have been integrated in order to better define the structural features of the continental crust in the Mt Amiata geothermal area. In this paper I propose the hypothesis that the structure of the crust in the Mt Amiata volcano-geothermal area derives from two main geological processes: (1) contractional tectonics related to the stacking of the Northern Apennines (Cretaceous–Early Miocene), (2) subsequent extensional collapse of the hinterland of the mountain chain, and related opening of the Northern Tyrrhenian Sea (Early Miocene–Quaternary). Compressional and extensional structures characterise the Mt Amiata region, although extensional structures dominate its geological framework. In particular the extension produced: (a) Middle-Late Miocene boudinage of the previously stacked tectonic units; (b) Pliocene–Quaternary normal faulting which favoured the emplacement of a magmatic body in the middle-upper crust; and (c) the eruption of the Mt Amiata volcano, which gave rise to an acid and intermediate volcanic complex (0.3–0.19 Ma). The extension produced the space necessary to accommodate the Middle-Late Miocene marine and continental sediments. Pliocene and Quaternary normal and transtensional faults dissected the previous structures and influenced the Early Middle Pliocene marine sedimentation within the structural depressions neighbouring the Mt Amiata volcano. The magmatic body was emplaced at depth (about 6–7 km) during the Pliocene extension, and produced the eruption of the Mt Amiata volcano during the Late Pleistocene. This gave rise to local uplift, presently reaching about 3,000 m, as well as a negative Bouguer anomaly (−16 mgal), both centred on the Mt Amiata area. The crustal dome shows a good correspondence with the convex shape of the regional seismic marker known as the K-horizon, which corresponds to the 450°C isotherm, and the areas with greatest heat flow. This is probably a consequence of the above-cited magmatic body presently in the process of solidification. A Late Pleistocene eruption occurred along a crustal fissure striking N50° (Mt Amiata Fault), which crosscuts the crustal dome. Hydrothermal circulation, proven by the occurrence of thermal springs and gas vents (mainly CO2 and H2S), mainly occurs along the Mt Amiata Fault both in the northeastern ans southwestern sides of the volcano.  相似文献   

18.
西北干旱区水资源与第四纪盆地系统   总被引:21,自引:0,他引:21       下载免费PDF全文
西北干旱区第四纪盆地主要是在中、新生代盆地基础上发展而成,一般可分为前山带山间断拗盆地和山前断拗盆地两大类,前者规模较小,后者规模较大,居主导地位。盆地构造形式大部分为单斜式不对称盆地,又可划分为单列型单斜式盆地和多列型单斜式盆地,包括部分地下隐伏盆地,形成盆地系统。盆地构造主要受区域深大断裂和新构造作用控制,具有明显的方向性和规律性。每条河流一般要流经2~3个盆地,形成由盆地系统构成的一个统一的水文系统。全流域的水循环系统和水资源系统,均受盆地系统的制约。因此,研究干旱区第四纪盆地系统,对合理开发利用水资源具有重要意义。  相似文献   

19.
Multidisciplinary Quaternary investigations in the Minusinsk Basin in the upper Yenisei River region and other southern Siberian continental depressions have produced evidence of prehistoric peopling pre‐dating the last glacial stage (>100 ka BP). Abundant ‘pebble tools’ and bone artefacts exposed from eroded alluvia of the Yenisei River terraces indicate repeated occupation of this territory since the Middle Pleistocene. A new stage of expansion of the early human occupation habitat occurred around the last interglacial (OIS 5e) by a Middle Palaeolithic (Neanderthaloid?) population characterized by a core and flake stone industry and open‐air occupation sites. The key camp/kill‐processing site at Ust‘‐Izhul’, dated to c. 125 ka BP and documenting complex behavioural activities, is so far the most complete in situ pre‐Late Palaeolithic site found in Siberia. This unique record provides new insights into the timing and the palaeoenvironmental conditions of the Pleistocene colonization of north‐central Asia.  相似文献   

20.
This work examines the connection between Quaternary tectonics and erosion/incision processes in the primary Tuscan‐Romagna watershed of the Northern Apennines, which essentially coincides with the topographic culmination of the Nero Unit structural ridge. Tectonic and geomorphic information were collected in the area where this ridge is crossed by the upper Tiber River course forming a deep gorge. Structural analysis and field mapping have revealed that the region experienced polyphase tectonics with superposed thrust folding events identifiable both at the map and mesoscopic scales. Hinterland‐SSW‐verging thrusts and thrust‐related folds deformed the whole thrust pile during the latest deformation phase. Backthrusts/backfolds controlled the development of intermountain basins nearby the main watershed during the Early Pleistocene and seemingly deformed, in the Tiber gorge, a low‐relief landscape developed in the Early Pleistocene (ca. 1.1 Ma). Successively, the upper Tiber River course area and Apennines axial zone underwent a generalized uplift, which is manifested by the deep incision of palaeo‐morphologies. This proposed sequence of events correlates well with the major geodynamic change of the Apennines revealed by an acceleration of uplift rates in the Middle–Late Pleistocene. This latter event may also correlate with increased rates of river incision recorded in Europe as a consequence of uplift and/or climate change. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

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